fatty acid oxidation (Decanoate)

Escherichia coli

Metabolic Pathway

Although enzymes of the pathway handle both short and long chain fatty acids, it is the long chain compounds that induce the enzymes of the pathway . Each turn of the cycle removes two carbon atoms until only two or three remain. When even-numbered fatty acids are broken down, a two-carbon compound remains, acetyl-CoA. When odd number fatty acids are broken down, a three-carbon residue results, propionylCoA. Unsaturated fatty acids, with cis double bonds located at odd-numbered carbon atoms, enter the main pathway of saturated fatty acid degradation by converting related metabolites of cis configuration and D stereoisomers, derived from breakdown of unsaturated fatty acids, to the trans- or L isomers of saturated fatty acid breakdown by an isomerase and an epimerase, respectively. When cis double bonds are located at even-numbered carbon atoms, such as linoleic acid (cis,cis(9,12)-octadecadienoic acid), after the fatty acid is degraded to the ten carbon stage an extra step is required to deal with the resulting compound, trans,δ(2)-cis,δ(4)decadienoyl-CoA. The enzyme 2,4-dienoyl-CoA reductase, converts this to trans,δ(2)decenoyl-CoA which enters the normal cycle at the point of the isomerase.
The order of the reaction is as follows:
a 2,3,4 saturated fatty acid is transformed into a 2,3,4 saturated fatty acyl CoA through a Long and short chain fatty acid CoA ligase. The 2,3,4 saturated fatty acyl CoA is then transformed into a trans 2 enoyl CoA. This enoyl can also be produced from a cis 3 enoyl CoA through a fatty acid oxidation protein complex. The trans 2 enoyl is transformed into a 3s 3 hydroxyacyl CoA through a 2,3 dehydroadipyl CoA hydratase. This same enzyme turns the product into a 3-oxoacyl-CoA. This is followed by the last step in the reaction when the oxoacyl-coa is turn into an acetyl coa+ a 2,3,4 saturated fatty acyl CoA through a 3-ketoacyl-CoA thiolase